Integrated mass air flow sensor and broadband silencer

Abstract

An integrated mass air flow sensor/broadband silencer assembly comprises a molded body having a plurality of walls formed therein. The molded body is over-wrapped with a layer of acoustic foam that, together with the plurality of walls, define a plurality of chambers within an interior volume of the assembly. A mass air flow sensor can be inserted into one of the chambers. The chambers are sized and spaced to provide a uniform velocity, low turbulence air flow to the sensor, and a minimally-restricted air flow to an internal combustion engine located downstream of the assembly.

1. An air induction assembly adapted to be incorporated in an air intake system of an internal combustion engine, said air induction assembly comprising:
 a housing; 
 a substantially cylindrical molded body fitted within said housing, said molded body having an upstream segment and a downstream segment, 
 a layer of wire mesh formed over a circumferential outer surface of the molded body; 
 a layer of acoustic foam formed over an outer surface of the wire mesh; and 
 a mass air flow sensor inserted into an inner volume of the molded body, wherein the molded body comprises: 
 a first wall extending along a longitudinal axis of the molded body, said first wall comprising a plurality of perforations within the upstream segment; 
 at least one second wall formed within said downstream segment orthogonal to the first wall and aligned with a longitudinal axis of the molded body; 
 a plurality of rings formed within the downstream segment, each ring concentrically aligned with respect to a longitudinal axis of the molded body and having a central circular opening; and 
 a mass air flow sensor flow tube formed within the upstream segment and aligned with a longitudinal axis of the molded body, said mass air flow sensor flow tube bifurcating the first wall within the upstream segment. 
 
     
     
       2. An air induction assembly according to  claim 1 , wherein the molded body is formed from a synthetic resin material. 
     
     
       3. An air induction assembly according to  claim 1 , wherein the each of the first wall, the second wall, the mass air flow sensor flow tube, and the plurality of rings have a thickness of from about 1.5 to 3 mm. 
     
     
       4. An air induction assembly according to  claim 1 , wherein the wire mesh comprises stainless steel. 
     
     
       5. An air induction assembly according to  claim 1 , wherein the wire mesh has a thickness of less than about 0.3 mm. 
     
     
       6. An air induction assembly according to  claim 1 , wherein the acoustic foam comprises ethylene propylene diene monomer. 
     
     
       7. An air induction assembly according to  claim 1 , wherein the acoustic foam has a thickness of from about 5 to 20 mm. 
     
     
       8. An air induction assembly according to  claim 1 , wherein an overall length of the assembly is from about 200 to 250 mm. 
     
     
       9. An air induction assembly according to  claim 1 , wherein an outer diameter of the assembly is from about 100 to 150 mm. 
     
     
       10. An air induction assembly according to  claim 1 , wherein the molded body comprises a pair of fastener receiving portions. 
     
     
       11. An air induction assembly according to  claim 1 , wherein the housing comprises an outlet duct of a filter box. 
     
     
       12. An air induction assembly according to  claim 11 , wherein the housing comprises a circumferentially-raised bead at a downstream end thereof. 
     
     
       13. An air induction assembly of  claim 1 , wherein the housing comprises a free-standing housing. 
     
     
       14. An air induction assembly according to  claim 13 , wherein the housing comprises circumferentially-raised beads at a downstream end and at an upstream end thereof. 
     
     
       15. An air induction assembly according to  claim 1 , wherein the length of the upstream segment is approximately equal to the length of the downstream segment. 
     
     
       16. An air induction assembly according to  claim 1 , wherein the size of the perforations is from about 0.1 to 5 mm. 
     
     
       17. An air induction assembly according to  claim 16 , wherein the size of the perforations is from about 0.1 to 2 mm. 
     
     
       18. An air induction assembly according to  claim 1 , wherein the perforations are sized and spaced to reduce the intensity of low frequency vibrations in the upstream segment. 
     
     
       19. An air induction assembly according to  claim 1 , wherein the mass air flow sensor is inserted into the mass air flow sensor flow tube via an aperture formed in the mass air flow sensor flow tube. 
     
     
       20. An air induction assembly according to  claim 1 , wherein the mass air flow sensor flow tube has an inner diameter of from about 25 to 45 mm. 
     
     
       21. An air induction assembly according to  claim 1 , wherein the mass air flow sensor flow tube has a length of from about 75 to 100 mm. 
     
     
       22. An air induction assembly according to  claim 1 , wherein the first wall comprises a semicircular cut away downstream of the mass air flow sensor flow tube. 
     
     
       23. An air induction assembly according to  claim 1 , wherein the assembly comprises from 3 to 6 rings. 
     
     
       24. An air induction assembly according to  claim 1 , wherein the diameter of each successive circular opening increases in a downstream direction. 
     
     
       25. An air induction assembly according to  claim 1 , wherein an axial spacing between each successive ring decreases in a downstream direction. 
     
     
       26. An air induction assembly according to  claim 1 , wherein the downstream segment comprises two separate parallel second walls that are each formed orthogonal to the first wall and which are aligned with a longitudinal axis of the molded body. 
     
     
       27. An air induction assembly according to  claim 1 , wherein the plurality of rings are sized and spaced to reduce the intensity of high frequency vibrations in the downstream segment. 
     
     
       28. A method of forming an air induction assembly adapted to be incorporated in an air intake system of an internal combustion engine, said method comprising:
 forming a substantially cylindrical molded body having an upstream segment and a downstream segment; 
 wrapping a layer of wire mesh over a circumferential outer surface of the molded body; 
 wrapping a layer of acoustic foam over an outer surface of the wire mesh to form a pre-assembly; 
 inserting the pre-assembly into a housing; and 
 inserting a mass air flow sensor inserted into an inner volume of the molded body to form the assembly; 
 
       wherein the molded body comprises:
 a first wall extending along a longitudinal axis of the molded body, said first wall comprising a plurality of perforations within the upstream segment; 
 at least one second wall formed within said downstream segment orthogonal to the first wall and aligned with a longitudinal axis of the molded body; 
 a plurality of rings formed within the downstream segment, each ring concentrically aligned with respect to a longitudinal axis of the molded body and having a central circular opening; and 
 a mass air flow sensor flow tube formed within the upstream segment and aligned with a longitudinal axis of the molded body, said mass air flow sensor flow tube bifurcating the first wall within the upstream segment. 
 
     
     
       29. The method of  claim 28 , further comprising securing the housing and the mass air flow sensor to the pre-assembly via fastener receiving portions formed in the pre-assembly using a plurality of fasteners.